First came the cracking sounds. Then windows started blowing out. • Before they knew it, guests felt the ground beneath Summer Bay Resort sinking into the earth near Disney World. • "It sounded like a fight — like multiple people with aluminum baseball bats who were swinging them against the windows, and then one window broke," said Maggie Ghamry, 27, visiting Summer Bay from Gainesville, Va., with a girlfriend and their children. • Ghamry said she grabbed everyone and they ran out of Building 104. What they saw outside, she said, was terrifying.

"You don't see a building every day twisting around like it was in a vortex and coming down around you, and seeing the room you would have slept in with three toddlers sink 50 feet into the ground and then two floors collapsing on top of them."

By early Monday, nearly a third of the structure at Summer Bay Resort had fallen into the "cover collapse'' sinkhole about 100 feet in diameter.

It was similar to the one that opened beneath a Seffner house in March, killing 37-year-old Jeffrey Bush.

All 105 guests staying in the villa were evacuated, as were those in the neighboring buildings. No injuries were reported. The villa, with 24 three-story units, was reported as a total loss.

Inspectors remained on the scene Monday afternoon to determine whether the other two buildings near the sinkhole would be safe to re-enter.

Lake County is among the most susceptible to sinkholes in the state because of its underlying hard formations made of material such as limestone, according to Todd Hammerle, a Florida Department of Transportation district maintenance engineer.

The first sign of trouble came about 10:30 p.m. Sunday. Security guard Richard Shanley had just started his shift, and he heard what sounded like shouting from a building.

A guest flagged him down to report that a window had blown out. Shanley reported it to management, and another window popped. The resort's staff decided to evacuate the villa.

Shanley said the building seemed to sink by 10 to 20 inches and bannisters began to fall off the building as he ran up and down three floors trying to wake up guests. One couple with a baby on the third floor couldn't get their door open and had to break a window to get out, he said.

"It's a scary situation," Shanley said, and guests credited him with saving lives by knocking on doors to awaken them. Inside, they heard what sounded like thunder. Evacuation took about 10 to 15 minutes, according to staff and witnesses.

Amy Jedele heard screams coming from one of the adjacent buildings around 10:30 p.m., and several minutes later, the sounds of sirens. She and her fiance, Darren Gade, went outside. "That's when you could hear the pops and the metal, the concrete and the glass breaking," she said.

The first portions of the building to sink were the walkways and the elevator shaft, Gade said.

"You could see the ground falling away from the building where the building started leaning," Gade said. "People were in shock to see a structure of that size just sink into the ground slowly. You could see the stress fractures up the side of the structure getting wider."

Then, as a part of the leaning building crumbled quickly into the ground, dust shot up around the site, amateur video of the collapse shows.

In one of the adjacent buildings, firefighters and police officers knocking on doors woke up Maggie Moreno of San Antonio. She couldn't fully open the door to her unit.

"It sounded like popcorn," said Moreno, who was visiting with her husband, daughter and two grandchildren. "The building was just snapping."

Luis Perez also was staying at a nearby building. He said he was in his room when the lights went off around 11:30 p.m. He said he was on his way to the front desk to report it when he saw firefighters and police outside.

"I started walking toward where they were at, and you could see the building leaning, and you could see a big crack at the base of the building," said Perez, 54, of New Jersey.

Over the next five hours, sections of the building sank into the ground.

Paul Caldwell, the development's president, said the resort gave all affected guests other rooms. Some visitors — many of whom had to leave their wallets, purses and other belongings behind in the quick evacuation — were given cash advances by Summer Bay.

There were no signs before Sunday that a sinkhole was developing, Caldwell said. He said the resort underwent geological testing when it was built about 15 years ago, showing the ground to be stable.

Caldwell said the U.S. Geological Survey was bringing in drilling and testing equipment Monday afternoon, but it will be mid-morning today before any information will be available about whether the sinkhole is growing.

Caldwell said resort officials will continue to keep buildings 104 — the one currently in the ground — 105 and 103 empty. "103 and 105 don't appear visually affected, but we don't know if that is the case," he said.

Information from the Orlando Sentinel and Associated Press was used in this report.

Much of Central Florida, especially the Interstate 4 corridor from Volusia County to Hillsborough County, has geology susceptible to sinkholes. The region has a history of activity, including a 320-foot wide, 90-foot deep sinkhole that consumed a Winter Park car dealership and home in 1981. Three years ago, sinkholes collapsed lanes of U.S. 27 east of Polk County. Most recently, a Seffner man was killed in March when a sinkhole opened beneath the bedroom where he was staying.